Engine starter gearing



March 17, 1953 D. L. ToBlAs 2,631,456

ENGINE STARTER GEARING Filed Sept. 20, 1951 IAA IN V EN TQR.

AT OHNEY Patented Mar. 17, 1953 Davide.. frobiassnlmina' N. fassignpno-Benaiz A iation sorncration, a corporation of `Delastilare application-september 20, 19.51, is erialNow247J443 Claims- :The present 'invention relates to eng-inestarter gearing and more particularly to ya, drive ofthe armeniatioally traversing vtype having 4novel mea-ns fior preventing premature v'demesh 4-o-f the drive lpinion.

starter gearing of-the above type in which the demeshing of the drive -pinion is controlled responsive to engine speed, it sometimes happens that sudden acceleration of the pinion by sporadio Yvigorous explosionsof the engine-may cause itsspeedto momentarily exceed the critical speed and cause demesh ofthe drive before the engine is reliably.self-operative.

is an object of the presen-tinvention to providea novel engine starter drive of the so called tanti-kickout type having mea-ns for prevent- .ing demefsh of vthe drive during periods ofrapid acceleration, even though the lpinion -m-o-mentarily rotates .faster than :th-,e critical sneed.

`It is another' object to providelsuch Ya device .which :the Speed-Controlled .device in the form of a spring-pressed latch which is disengaged'by centrifugal for-ce, and theaccelerationcontrolled .device 'is *in theiorm v.of ,a ,dotant opposing reileaseoftheiatch.

Further objects and advantages will be apparent dfrom the follOWing description taken in connecti-on with Athe accompanying `drawing in which:

Fig. 1 is a side elevation partly broken away land in section of a preferred embodiment of *the invention showing the parts in Yidle position;

Fig. 2 is an enlarged 7 detail in section take-n substantially on the line 2-2 of Fig, 1 showing the latch mechanism;

Fig. 3 is a detail similar to Fig. 2 showing the parts in cranking position;

Fig. 4 is a similar detail showing the partsrin the positions assumed wh-en the engine res and accelerates the drive pinion;

Fig. 5 is a similar detail showing the partsjas positioned during the demeshing movement of th-e drive.

In Fig. 1 of the drawing there is illustrated a power shaft I on which a sleeve 2 having a drive head 3 is xedly mounted as by means of a cross pin 4. A driving overrunning clutch mem-ber 5 is slidably journalled on the sleeve 2 and yieldingly connected to the drive head 3 of the sleeve by means of a spring VIi the ends of which are connected to the drive head and clutch member l by the anchor -plates 1 and 8 respectively. The spring 6 isv maintain-ed under light initial compression by means of a lock ring 9 seated in a groove l I in the sleeve and received by a counterbore I2 in the driving clutch member 5.

A .screw 4shaft I3 is--slidablyY-journalled on the sleeve '2 and -is provided with overrunning clutch teeth fI-iI vadapted to cooperate with similar lclutch teeth 45 on -th'e'clutchmemberi -A stop ring l"f6 ismountedon the end of the sleeve Av2 and isretained thereon Iby pa `lock-,ring -I'L 4A light compression Vspring v1If8`is located between `the stop ring I6 and `the end of the screw shaft 13, andis operative dlio-normally kmaintain the clutch teeth Hi, I5 in engagement. A 'thrust A.vas'her '|19 :is preferably interposed between the clutch spring' I8 andthe end 'off the screw shaft.

A Vpinion '12 I -is slidably jj ournalled on the power shaft I lfor movement into and out of mesh with an engine 4gear "2;2. A -'barrel member 12.3 isanchored al? 011e .end to -the V.pinion as 'indicated at 2K3 and provided at its other en-d .with s101352 5 adapted to receive 'lugs 216 `extending radially from a .control nut 1.2.1 threaded on .the .screw shaft I3, the control nutbeing retained -in the barrel by a lock ring 28.

Means are provided forpnposing the demeshing movement of 'the pinion when yit is rotating below a predetermined vcrit-,ical speed. As jhere Shown this meansis inthe form of afl-atcb :member 2.9 Slidablv .mountedfor radial movement the control nut ,2:1 againstga compression .spring and arranged 'to `drop into anotch .3'2 .in the screwshaft ywhen vthe .pinion is moved into meshflgrpostion.

`lVLea-Iis are Im10vided for preventing `disengagement of the latoh 129 ,from the .notch `32 "by `centrifugal .force while the pinion and .its associated parts -are being accelerated by the engine gaat. V.As .Shown in Fig. `2 this means is in .the

f form of a -detent'33 sii-dably mounted in the control nut 21 for tangential movement into 'and out of engagement with the latch 29. The detent 33 is located on the forward side of the latch 29 as respects the direction of rotation of the parts, as indicated by the arrow a and is normally maintained out of engagement with the latch by a spring 34. The latch 29 is formed with a shoulder 35 in such position that when the latch is moved into the notch 32 of the screw shaft, said shoulder is located radially inward from the path of the detent 33 as shown in Fig. 3, sudden accele-ration of the pinion `'and control nut is thereby effective to move the detent 33 into engagement with the latch 29 above the shoulder 35 as shown in Figure 4, thereby opposing the releasing movement of the latch.

In operation, starting withthe parts in the positions shown in Figs. 1 and 2, rotation of the power shaft I in the direction of the arrow a causes the control nut 21 to be traversed to the left in Fig. 1 so as to mesh the pinion 2| with the engine gear 22, after which the latch 29 enters the notch 3'2 in the screw shaft so as to hold the pinion in mesh. The meshing movement of the control nut 2'l is limited by the stop ring I6, after which rotation of the pinion is transmitte to the engine gear to crank the engine.

When the engine res, the acceleration of the engine gear transmitted to the pinion causes the pinion, barrel and control nut to overrun the power shaft which would normally tend to cause the control nut to be traversed back toward idle position. This movement, however, is prevented by the engagement of the latch 29 in the notch 32 of the screw shaft so that the screw shaft is forced to rotate with the control nut, such rotation being permitted by the overrunning clutch connection I4, I5. If the initial explosions are vigorous, the rotation of 4the pinion and control nut may exceed the critical speed necessary to cause the latch 29 to move outward by centrifugal force and permit the parts to be traversed back to idle position. During the period of ac celeration however, the inertia of the detent 33 causes it to compress the spring 34 and move into the position shown in Fig. 4 whereby the latch is maintained in engagement irrespective of the speed of rotation of the parts. When the engine becomes reliably self-operative so that its rotational speed does not uctuate widely, the spring 34 moves the detent 33 out of engagement with the latch 29 which is thus permitted to move radially outward and allow the pinion and its associated parts to return to idle position.

Although but one embodiment of the invention has been shown and described in detail it will be understood that other embodiments are possible and changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive, a power shaft, a pinion slidably journalled on the power shaft for movement into and out of mesh with an engine gear, means responsive to acceleration of the power shaft for traversing the pinion into mesh with the engine gear and then rotating the pinion to crank the engine, said means being operative to demesh the pinion when its speed exceeds that of the power shaft, means for preventing demeshing of the pinion below a predetermined critical speed, and means responsive to a predetermined rate of acceleration of the pinion for maintaining the effectiveness of said demesh-preventing means above said critical speed; including fur- '4 ther an overrunning clutch between the power shaft and the pinion-traversing means.

2. In an engine starter drive, a power shaft, a pinion slidably journalled on the power shaft for movement into and out of mesh with an engine gear, means responsive Vto acceleration of the power shaft for traversing the pinion into mesh with the engine gear and then rotating the pinion to crank the engine, said means being operative to demesh the pinion when its speed exceeds that of the power shaft, means for preventing demeshing of the pinion below a predetermined critical speed, and means responsive to a predetermined rate of acceleration of the pinion for maintaining the effectiveness of said demeshpreventing means above said critical speed; in which the demesh-preventing means is in the form of a centrifugallyfreleased latch, and the means for maintaining fthe effectiveness of the latch is .in the form of a tangentially movable detent engageable with the latch.

3. In an engine starter drive a power shaft, a',

screw shaft rotatably mounted thereon, yielding means connecting the screw shaft to rotate with the power shaft, a control nut on the screw shaft,

a pinion slidably journalled on the power shaft for movement into and out of mesh with an engine gear, a barrel member connecting the control nut and pinion, a latch member mounted in the control nut for radial movement into and out of engagement with the screw shaft, and a detent mounted in the controlnut for tangential movement into and out of engagement with the latch.

4. An engine starter drive as set forth in claim 3 including further a spring normally urging the latch into engagement with the screw shaft, and said screw shaft having a notch for receiving the end of the latch to oppose demeshing movement of the control nut.

5. An engine starter drive as set forth in claim 3 in which the detent is located on the forward side of the latch as respects rotation of the control nut and including further a spring normally holding the detent out of engagement with the latch.

DAVID L. TOBIAS.

REFERENCES CITED UNITED STATES PATENTS Name Date Buxton Oct. 19, 1943 Number 

